Test strips are often used for testing for the presence of an analyte of interest. The analyte may be, without limitation, a compound, virus, bacteria, protein etc. A sample to be tested is applied to the test strip. The test strip comprises one or more measurement regions where a response of the test strip to the sample is visibly observed. In some instances the sample is a fluid. However the sample may also be a solid, such as a powder. The term “test strip” may be used interchangeably to describe a device which contains at least one colour change region in response to an analyte and therefore may include a microfluidic cartridge.
In order to measure the response of the test strip to the sample the colour change may be analysed by eye as often the case in a pH test, however, such an approach only provides for a subjective determination. For a quantifiable output the test strip may be inserted into a dedicated reading device where it is subjected to predetermined illumination conditions so that the response of the measurement region(s) can be measured. However such dedicated test strip reading devices are expensive and require the user to have access to the dedicated equipment.
It is also known to use a non-dedicated reading device for reading a test strip. US2006222567 discloses a testing device for use with a mobile processing device such as a mobile phone having a camera to capture an image of an analyte reaction product. Software executing on the mobile phone determines the presence or quantity of the analyte in the reaction product from the image. As noted in paragraph 103 of this document, the software is specifically adapted for performing the analyte test.
US 2007/0273928 discloses a test strip which includes a grey scale calibration pattern which corresponds to one of 49 calibration codes. A memory module of a reading device includes a grey scale permutation matrix with a plurality of calibration codes by which a calibration of the test strip may be determined. However, the reading device requires the permutation matrix and knowledge of a test to be performed.
It is an object of embodiments of the invention to at least mitigate one or more of the problems of the prior art.